Anatomy of the Spine

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The vertebral column, also called the backbone, is made up of 33 vertebrae that are separated by spongy disks and classified into four distinct areas. The cervical area consists of seven bony parts in the neck; the thoracic spine consists of 12 bony parts in the back area; the lumbar spine consists of five bony segments in the lower back area; five sacral* bones; and four coccygeal* bones (the number of coccygeal bones can vary from five to three).

(* By adulthood, the five sacral vertebrae fuse to form one bone, and the four coccygeal vertebrae fuse to form one bone.)